Our long term interest is understanding adhesive interactions between oral epithelial cells and basement membranes in dentition. Laminin-5 is a basement membrane ligand for epithelial cells in skin and is associated with the formation of hemidesmosomes. In its absence, a number of skin disorders are known to occur. During tooth formation, laminin-5 is expressed in preameloblasts and ameloblasts, the enamel producing cells. It is also found in the junctional epithelium (JE), a protective adhesive barrier between the tooth and connective tissue in the gingiva. We are interested in determining the role that ln-5 plays in enamel production and/or secretion and in the adhesive properties possessed by the JE. To do this we will: (1) determine the pattern of ln-5 expression in the developing and adult mammalian tooth, (2) elucidate the function of ln-5 in the differentiation of preameloblasts and in the secretion of enamel, and (3) determine the roles of ln-5 in regulating different cell behaviors such as adhesion versus migration in the JE. By these approaches, we hope to assess the contribution of ln-5 in tooth development. Clarifying these contributions will give us a better understanding of periodontal disease associated with the function of adhesion molecules and lay the foundations for approaches to healing and regeneration.